U.S. patent application number 14/649271 was filed with the patent office on 2015-11-05 for allocation of physical cell identification.
The applicant listed for this patent is NOKIA SOLUTIONS AND NETWORKS OY. Invention is credited to Ian Dexter GARCIA.
Application Number | 20150319611 14/649271 |
Document ID | / |
Family ID | 47324134 |
Filed Date | 2015-11-05 |
United States Patent
Application |
20150319611 |
Kind Code |
A1 |
GARCIA; Ian Dexter |
November 5, 2015 |
Allocation of Physical Cell Identification
Abstract
A method includes generating, by a network element, a radio map
of a single-frequency network having multiple cells. The radio map
represents power levels of radio signals at several locations in
the network. A first function is selected to be applied, wherein
the first function is based on the radio map and includes physical
cell identity, PCI, modulo 3 values for the multiple cells as
input. Different combinations of the PCI modulo 3 values are
applied in the first function. Each candidate PCI modulo 3 value is
selected from a group of three available options. An output of the
first function is determined with respect to each combination. It
is determined which combination provides the output fulfilling a
predefined criterion. Those PCI modulo 3 values, which correspond
to the output fulfilling the predefined criterion, are allocated to
the multiple cells in order to reduce interference between primary
synchronization sequences.
Inventors: |
GARCIA; Ian Dexter;
(Palatine, IL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
NOKIA SOLUTIONS AND NETWORKS OY |
Espoo |
|
FI |
|
|
Family ID: |
47324134 |
Appl. No.: |
14/649271 |
Filed: |
December 4, 2012 |
PCT Filed: |
December 4, 2012 |
PCT NO: |
PCT/EP2012/074352 |
371 Date: |
June 3, 2015 |
Current U.S.
Class: |
370/329 |
Current CPC
Class: |
H04W 16/18 20130101;
H04W 8/26 20130101 |
International
Class: |
H04W 8/26 20060101
H04W008/26; H04W 16/18 20060101 H04W016/18 |
Claims
1. A method, comprising: generating, by a network element, a radio
map of a single-frequency network having a plurality of cells,
wherein the radio map represents power levels of radio signals at
several locations in the network; selecting a first function to be
applied, wherein the first function is at least partly based on the
radio map and comprises physical cell identity, PCI, modulo 3
values for the plurality of cells as input variables; applying
different combinations of the PCI modulo 3 values in the first
function, wherein each candidate PCI modulo 3 value is selected
from a group of three available options; determining the output of
the first function with respect to each combination; determining
which combination provides the output fulfilling a predefined
criterion; and allocating those PCI modulo 3 values, which
correspond to the output fulfilling the predefined criterion, to
the plurality of cells in order to reduce the interference between
primary synchronization sequences.
2. The method of claim 1, wherein the radio map represents at least
one of the following for each of the several locations: the power
level of the radio signal with respect to the serving cell, the
power level of interference, noise level.
3. The method of claim 1, further comprising: receiving radio map
related parameters from a user equipment, wherein the radio map
related parameters are based on radio signal measurements performed
by the user equipment; and generating the radio map on the basis of
the received parameters.
4. The method of claim 1, further comprising: estimating radio map
related parameters on the basis of mathematical simulations; and
generating the radio map on the basis of the estimated
parameters.
5. (canceled)
6. The method of claim 1, wherein the first function disregards the
interference caused to a first cell by a second cell when the first
cell and the second cell have different PCI modulo 3 values
according to the current combination.
7. The method of claim 1, wherein the output of the first function
represents a cumulative interference detection rate or a cumulative
interference value among the plurality of cells, wherein the first
function takes into account the power levels of interference
determined for each of the several locations on the basis of the
radio map.
8. The method of claim 1, wherein the output of the first function
represents a cumulative value related to a signal-to-interference
ratio or to a signal-to-interference-plus-noise ratio, wherein the
first function takes into account the corresponding ratios
determined for each of the several locations on the basis of the
radio map.
9. The method of claim 1, wherein the output of the first function
represents a cumulative throughput in the network, wherein the
first function takes into account the throughputs determined for
each of the several locations on the basis of the radio map.
10. The method of claim 9, further comprising: after having
allocated the PCI modulo 3 values for the plurality of cells,
performing the following: determining which of the plurality of
cells have the same PCI modulo 3 value; selecting a second function
to be applied, wherein the second function is at least partly based
on the radio map and comprises, as input variables, PCI modulo 30
values for the cells having the same PCI modulo 3 value; applying
different combinations of the PCI modulo 30 values in the second
function, wherein each candidate PCI modulo 30 value is selected
from a group of at thirty available options; determining the output
of the second function with respect to each combination;
determining which combination provides the output fulfilling a
second predefined criterion; and allocating those PCI modulo 30
values, which correspond to the output fulfilling the second
predefined criterion, to the cells having the same PCI modulo 3
value in order to reduce the interference between different
demodulation reference signals.
11. The method of claim 10, further comprising: narrowing the
number of available options for the candidate PCI modulo 30 values
by requiring that each candidate PCI modulo 30 value for a certain
cell fulfills a following condition: a modulo 3 arithmetic
performed for the candidate PCI modulo 30 value is the same as the
allocated PCI modulo 3 value for the certain cell.
12. (canceled)
13. The method of claim 10, wherein the second function disregards
the interference caused to a first cell by a second cell when the
first cell and the second cell have different PCI modulo 30 values
according to the current combination.
14. The method of claim 10, wherein the second function is the same
as the first function.
15. The method of claim 1, further comprising: determining a PCI
for each of the plurality of cells on the basis of at least one of
the following: the allocated PCI modulo 3 values and the allocated
PCI modulo 30 values; and allocating the determined PCI for each of
the plurality of cells.
16. An apparatus, comprising: at least one processor and at least
one memory including a computer program code, wherein the at least
one memory and the computer program code are configured, with the
at least one processor, to cause the apparatus at least to:
generate a radio map of a single-frequency network having a
plurality of cells, wherein the radio map represents power levels
of radio signals at several locations in the network; select a
first function to be applied, wherein the first function is at
least partly based on the radio map and comprises physical cell
identity, PCI, modulo 3 values for the plurality of cells as input
variables; apply different combinations of the PCI modulo 3 values
in the first function, wherein each candidate PCI modulo 3 value is
selected from a group of three available options; determine the
output of the first function with respect to each combination;
determine which combination provides the output fulfilling a
predefined criterion; and allocate those PCI modulo 3 values, which
correspond to the output fulfilling the predefined criterion, to
the plurality of cells in order to reduce the interference between
primary synchronization sequences.
17. The apparatus of claim 16, wherein the radio map represents at
least one of the following for each of the several locations: the
power level of the radio signal with respect to the serving cell,
the power level of interference, noise level.
18. The apparatus of claim 16, wherein the at least one memory and
the computer program code are configured, with the at least one
processor, to cause the apparatus further to: receive radio map
related parameters from a user equipment, wherein the radio map
related parameters are based on radio signal measurements performed
by the user equipment; and generate the radio map on the basis of
the received parameters.
19. The apparatus of claim 16, wherein the at least one memory and
the computer program code are configured, with the at least one
processor, to cause the apparatus further to: estimate radio map
related parameters on the basis of mathematical simulations; and
generate the radio map on the basis of the estimated
parameters.
20. (canceled)
21. The apparatus of claim 16, wherein the first function
disregards the interference caused to a first cell by a second cell
when the first cell and the second cell have different PCI modulo 3
values according to the current combination.
22. The apparatus of claim 16, wherein the output of the first
function represents a cumulative interference detection rate or a
cumulative interference value among the plurality of cells, wherein
the first function takes into account the power levels of
interference determined for each of the several locations on the
basis of the radio map.
23. The apparatus of claim 16, wherein the output of the first
function represents a cumulative value related to a
signal-to-interference ratio or to a
signal-to-interference-plus-noise ratio, wherein the first function
takes into account the corresponding ratios determined for each of
the several locations on the basis of the radio map.
24. The apparatus of claim 16, wherein the output of the first
function represents a cumulative throughput in the network, wherein
the first function takes into account the throughputs determined
for each of the several locations on the basis of the radio
map.
25. The apparatus of claim 16, wherein the at least one memory and
the computer program code are configured, with the at least one
processor, to cause the apparatus further to: after having
allocated the PCI modulo 3 values for the plurality of cells,
performing the following: determine which of the plurality of cells
have the same PCI modulo 3 value; select a second function to be
applied, wherein the second function is at least partly based on
the radio map and comprises, as input variables, PCI modulo 30
values for the cells having the same PCI modulo 3 value; apply
different combinations of the PCI modulo 30 values in the second
function, wherein each candidate PCI modulo 30 value is selected
from a group of at thirty available options; determine the output
of the second function with respect to each combination; determine
which combination provides the output fulfilling a second
predefined criterion; and allocate those PCI modulo 30 values,
which correspond to the output fulfilling the second predefined
criterion, to the cells having the same PCI modulo 3 value in order
to reduce the interference between different demodulation reference
signals.
26. The apparatus of claim 25, wherein the at least one memory and
the computer program code are configured, with the at least one
processor, to cause the apparatus further to: narrow the number of
available options for the candidate PCI modulo 30 values by
requiring that each candidate PCI modulo 30 value for a certain
cell fulfills a following condition: a modulo 3 arithmetic
performed for the candidate PCI modulo 30 value is the same as the
allocated PCI modulo 3 value for the certain cell.
27. (canceled)
28. The apparatus of claim 25, wherein the second function
disregards the interference caused to a first cell by a second cell
when the first cell and the second cell have different PCI modulo
30 values according to the current combination.
29. The apparatus of claim 25, wherein the second function is the
same as the first function.
30. The apparatus of claim 16, wherein the at least one memory and
the computer program code are configured, with the at least one
processor, to cause the apparatus further to: determine a PCI for
each of the plurality of cells on the basis of at least one of the
following: the allocated PCI modulo 3 values and the allocated PCI
modulo 30 values; and allocate the determined PCI for each of the
plurality of cells.
31. (canceled)
32. A computer program product embodied on a distribution medium
readable by a computer and comprising program instructions which,
when loaded into an apparatus, execute the method according to
claim 1.
Description
FIELD
[0001] The invention relates generally to mobile communication
networks. More particularly, the invention relates to allocation of
physical cell identities (PCI).
BACKGROUND
[0002] In the LTE air interface, a physical (-layer) cell identity
(PCI) is used for cell identification and for channel
synchronization. Thus, the PCI planning may affect the performance
of the network, especially in a scenario with overlapping cells.
For example, from the point of view of an operator, it may be very
important to perform the PCI planning as optimally as possible in
order to provide an efficient and a customer-friendly communication
network.
BRIEF DESCRIPTION OF THE INVENTION
[0003] According to an aspect of the invention, there is provided a
method as specified in claim 1.
[0004] According to an aspect of the invention, there are provided
apparatuses as specified in claims 16 and 31.
[0005] According to an aspect of the invention, there is provided a
computer program product as specified in claim 32.
[0006] According to an aspect of the invention, there is provided a
computer-readable distribution medium carrying the above-mentioned
computer program product.
[0007] According to an aspect of the invention, there is provided
an apparatus comprising processing means configured to cause the
apparatus to perform any of the embodiments as described in the
appended claims.
[0008] According to an aspect of the invention, there is provided
an apparatus comprising a processing system configured to cause the
apparatus to perform any of the embodiments as described in the
appended claims.
[0009] According to an aspect of the invention, there is provided
an apparatus comprising means for performing any of the embodiments
as described in the appended claims.
[0010] Embodiments of the invention are defined in the dependent
claims.
LIST OF DRAWINGS
[0011] In the following, the invention will be described in greater
detail with reference to the embodiments and the accompanying
drawings, in which
[0012] FIG. 1 presents a communication network according to an
embodiment;
[0013] FIGS. 2, 4, 5 and 6 show methods according to some
embodiments;
[0014] FIG. 3 shows a radio map according to an embodiment;
[0015] FIG. 7 shows an embodiment related to allocation of physical
cell identities to several cells, according to an embodiment;
and
[0016] FIG. 8 illustrates an apparatus, according to an
embodiment.
DESCRIPTION OF EMBODIMENTS
[0017] The following embodiments are exemplary. Although the
specification may refer to "an", "one", or "some" embodiment(s) in
several locations of the text, this does not necessarily mean that
each reference is made to the same embodiment(s), or that a
particular feature only applies to a single embodiment. Single
features of different embodiments may also be combined to provide
other embodiments.
[0018] The embodiments of the invention are applicable to a
plurality of communication networks regardless of the applied radio
access technology. For example, at least one of the following radio
access technologies (RATs) may be applied: ong term evolution
(LTE), and/or LTE-advanced (LTE-A). The present embodiments are
not, however, limited to these protocols.
[0019] As shown in FIG. 1, a typical cell planning of a network 100
may be based on three-sector sites, such as eNBs 102, 104, 106.
This means that each site 102, 104 and 106 provides three cells
directed to different directions, as shown in FIG. 1 with solid,
dashed and dotted arrows, respectively. However, the network 100
may also comprise two-sector sites and/or omni-directional (single
sector) sites (although not shown). Each eNB 102, 104, 106, may be
connected via an S1 interface to an evolved packet core (EPC), more
specifically to a mobility management entity (MME) and to a system
architecture evolution gateway (SAE-GW). The MME is a control plane
for controlling functions of non-access stratum signaling, roaming,
authentication, tracking area list management, etc., whereas the
SAE-GW handles user plane functions including packet routing and
forwarding, idle mode packet buffering, a connection to Internet,
etc.
[0020] Each of the three sectors (e.g. cells, each represented with
a hexagonal block in FIG. 1) may have a physical-layer cell
identifier (PCI). The determination of the PCI for a cell may be
based on two aspects: a physical-layer cell identity group number
N.sub.ID1 {0, 1, . . . , 167} and a physical-layer cell identity
number N.sub.ID2 {0, 1, 2}. The PCI may then be determined on the
basis of the N.sub.ID1 and the N.sub.ID2 as follows:
PCI=(3.times.N.sub.ID1)+N.sub.ID2,
which implies 504 possible values. Assuming N.sub.ID1=1 and the
N.sub.ID1=2 then the PCI for the cell is PCI=3*2+1=7.
[0021] The N.sub.ID1 may define a secondary synchronization
sequence (SSS), whereas the N.sub.ID2 may define a primary
synchronization sequence (PSS), corresponding to 1.sup.st,
2.sup.nd, and 3.sup.rd PSS groups on the basis of PCI modulo 3 (PCI
mod 3) arithmetic. Members of the same PCI mod 3 group have the
same PCI mod 3 value, i.e. either 0, 1, or 2. Consequently,
according the specification of the LTE, cells with the same PCI mod
3 in the single frequency layer network 100 have the same PSS
sequence. Further, the cells may have the same time-frequency
location of the cell-specific reference signals (CRS).
[0022] In addition, a PCI modulo 30 (PCI mod 30) arithmetic may be
determined for each PCI candidate. This may be beneficial so that
uplink reference signal collisions, such as collisions of physical
uplink control channel (PUCCH) demodulation reference signals
(DMRS) may be avoided, as will be explained later. Here it may be
noted that the PUCCH DMRS sequences may be constructed from
Zadoff-Chu sequences which are divided into 30 groups. Roughly,
this means that there are 30 different base sequences that may be
used as the DMRS. Members of the same PCI mod 30 have the same PCI
mod 30 value, i.e. one of {0, 1, . . . , 29}. For cells with the
same PCI mod 30, the cells may have the same DMRS sequence group
number.
[0023] Cell synchronization may be the very first step when user
equipment 108 wants to camp on a given cell. The user equipment 108
may be e.g. a user terminal (UT), a computer (PC), a laptop, a
tabloid computer, a cellular phone, a mobile phone, a communicator,
a smart phone, a palm computer, or any other communication
apparatus. From the synchronization, the UE 108 acquires the PCI,
time slot and frame synchronization, which may enable the UE 108 to
obtain system information blocks (SIB) from the network 100. During
the synchronization, the UE 108 may first find the PSS. From the
PSS, the UE 108 may also be able to obtain the N.sub.ID2 (e.g. a
value from a group {0, 1, 2}). In the next step, the UE 108 may
acquire the SSS symbols. From the SSS, the UE 108 may be able to
obtain the N.sub.ID1 (e.g. a value from a group {0, 1, . . . ,
167}). Using the N.sub.ID1 and the N.sub.ID2, the UE 108 may
acquire knowledge of the PCI for the cell. Once the UE knows the
PCI for the cell, it may also know the location of the
cell-specific reference signals (CRS) used in channel estimation,
cell selection/reselection and handover procedures.
[0024] From the above it is clear that allocating the PCIs (e.g.
allocating the N.sub.ID1 and the N.sub.ID2 for the cells) is
important from the point of view of the performance of the network
100. For example, looking at FIG. 1, it may be seen that the UE 108
locates in the area 110 in which each of the eNB 102, 104, 106
provides coverage to. In other words, three cells overlap in the
area 110 where the UE 108 is located. Let us further assume that at
least some of the overlapping cells in the area 110 have the same
N.sub.ID1 and/or N.sub.ID2. As a result, during synchronization in
the network 100, the overlap of the PSSs and/or the SSSs from
different eNBs 102, 104, 106 may cause significant degradation in
the detection of the eNBs 102, 104, 106. This may lead to poor key
performance indicators (KPIs), especially for UEs at the
cell-edge.
[0025] A conventional approach to avoid such CRS/PSS/SSS/DMRS
collisions for three-sector site deployments is to assign a
different PCI mod 3 (i.e. different N.sub.ID2) to cells of the same
site. For single-sector deployments, the conventional approach to
avoid collisions is by visual inspection. However, in these
approaches, the collisions are not optimally avoided.
[0026] In order to improve the network performance and the KPIs, an
improved solution for the allocation of the PCIs is needed which
takes into account radio frequency signal levels in the network
100. Therefore, it is proposed, as shown in step 200 of FIG. 2, to
generate, by a network element, a radio map of the single-frequency
network 100 having a plurality of cells. Reuse of frequencies may
not be an option in case the network 100 is a single-frequency
network. Thus, the overlap of cells of the same frequency may be
inevitable. The overlapping cells may even be provided by different
operators as long as the cells are at the same frequency. The
network element may be any apparatus/entity in the network
responsible of the allocation of the PCIs to the cells in the
network 100. Let us look further at what the radio map may
represent and how such radio map may be generated with reference to
FIGS. 3 and 4.
[0027] In an embodiment, the radio map 300 of FIG. 3 may represent
power levels of radio signals at several locations in the network
100. The power levels may be, for example, reference signal
received power (RSRP) levels and/or received signal level (RSL).
The map may thus represent samples of RSRP/RSL levels at different
times and/or locations. For each sample, the RSRP/RSL from each
detected (or detectable) cell/eNB 102, 104, 106 and the
corresponding cell ID are recorded. It may be, for example, that a
cell located far away from another cell does not provide any signal
coverage to the latter cell. In such case, no signal from the
former cell is detected in the latter cell. It should be noted also
that instead of the downlink RSRP/RSL, the uplink signal power
level may be used. As the RSRP/RSL are detected from as many cells
as detected for each sample/location, the radio map may comprise
information of inter-cell interference at the several locations in
the network 100.
[0028] The radio map 300 may be generated on the basis of actual
measurements (e.g. measurements from drive test logs of the UE 308
or measurement report logs of the eNB 102, 104, 106). For example,
for each of the several locations, marked with crosses in FIG. 3, a
power level determination may be performed. In one embodiment, this
takes place by the UE 308 travelling around the network 100 and
making measurements. As indicated in FIG. 4, according to this
embodiment, the network element may in step 400 receive radio map
related parameters or parameter values from the UE 308, wherein the
radio map related parameters/values are based on radio signal
measurements performed by the UE 310. Further, such radio signal
level values at different locations may also be obtained by
collecting the measurement report radio resource control (RRC)
messages sent by several UEs. Thereafter, in step 404, the network
element may in step 404 generate the radio map on the basis of the
received parameters/values. Further, the network element may
receive information indicating identities of the cells providing
the radio signals corresponding to the power levels. Further, the
network element may receive information indicating the location in
network 100 corresponding to the measurement.
[0029] In another embodiment, the radio map 300 may be generated on
the basis of radio frequency (RF) planning tool and/or simulation
predictions instead of or in addition to the actual measurements.
The planning tools may comprise, e.g., tools like Atoll (by Forsk)
and Planet (by Mentum) which may create predictions through
simulations. As indicated in FIG. 4, according to this embodiment,
the network element may estimate radio map related parameters or
parameter values on the basis of mathematical simulations in step
402 and generate the radio map 300 on the basis of the estimated
parameters/values in step 404.
[0030] There may be many locations in the network 100. There may
even be many locations inside a single cell, as shown with the
crosses in FIG. 3. For each of the several locations, in an
embodiment, the radio map 300 represents at least one of the
following, as shown with the block 318 of FIG. 3: the power level
310 of the radio signal with respect to the serving cell, the power
level 312, 314 of interference, noise level 316.
[0031] Let us assume that there are three eNBs 102, 104, and 106
and that the eNB 106 provides the best signal quality at the
location 306 (i.e. eNB 106 is the serving cell as indicated with
solid arrow in FIG. 3). In such case, the radio map 300 may
indicate for the location 306 the power level 310 of the desired
signal from the eNB 106. Further, it may be detected by the UE 308
in the location 306 that the eNBs 102 and 104 may provide
interfering radio signals. The UE 308 or simulations may identify
each interference source for each location. Thus, as shown with the
block 318, the radio map may further indicate the power level 312
of the interference from the eNB 102 and separately the power level
314 of the interference from the eNB 104. Regarding the
interference, it may be noted that the sources of interference in
the location 302 may be the eNBs 104 and 106 (assuming the eNB 102
is the serving eNB) and in the location 304 the interfering eNBs
may be the eNBs 102 and 106 (assuming the eNB 104, being the
closest eNB, is also the serving eNB). It should be noted that in
case of several cells, the radio map 300 may represent the
individual interference levels with respect to each of the
plurality of cells. For the sake of simplicity, the cells are not
depicted in FIG. 3, only eNBs 102, 104, 106 are. Further, each
location may also be characterized with a detected or predicted
noise level 316. Accordingly, the proposal may enable predicting
CRS/PSS/PUCCH DMRS and avoiding collisions by taking into account
RF signal level based on drive tests (measurements) or RF planning
tool predictions, as will be explained.
[0032] Let us now look at the proposal of FIG. 2 further. In step
202, the network element, e.g. a PCI mod 3 allocation
circuitry/module of the network element, selects a first function
to be applied, wherein the first function is at least partly based
on the radio map and comprises PCI modulo 3 values for the
plurality of cells as input variables. There are several options
for the first function, as will be described later. The choice of
the function to be applied may be arbitrary, or it may depend on
the information included in the radio map 300.
[0033] In an embodiment, the first function comprises parameters
related to interference levels 312, 314 with respect to the
plurality of cells in the network 100. Additionally or instead, in
an embodiment, the first function comprises parameters related to
serving cell signal levels 310. Additionally or instead, in an
embodiment, the first function comprises parameters related to
noise levels 316 at several locations in the network 100.
Additionally or instead, in an embodiment, the first function
comprises parameters related to throughput levels with respect to
the plurality of cells in the network 100. Each of these parameters
may be determined on the basis of the radio map 300 for each of the
cells of the network 100 at several locations in the network 100,
and possibly for several time instants.
[0034] The first function may comprise the PCI mod 3 values for the
plurality of cells as input variables. Thus, the output of the
first function may depend on what PCI mod 3 values are inputted. In
step 204, different combinations of the PCI modulo 3 values may be
applied to the first function. As the term modulo 3 refers, each
candidate PCI mod 3 value is selected from a group of three
available options. In an embodiment, these available options are
{0, 1, 2}.
[0035] Then, in step 206, the output of the first function with
respect to each combination is determined. For example, if the
network 100 has nine cells as shown in FIG. 1, each combination
comprises nine numbers (each being 0, 1, or 2). I.e. each of the
cells is given one possible PCI mod 3 value in one combination.
Each combination may be tested and the output may be determined and
recorded. It should be noted that the candidate PCI mod 3 values
tested for the cells affect the output of the function for example
because two cells having different PCI mod 3 values do not
interfere each other, for example, from the point of view of the
PSS. As the function is based on the radio map and may thus
comprise parameters representing power levels of radio signals
(both desired signal and the interfering signals), the output of
the function may depend on which interference signals are taken
into account, as will be described later. In an embodiment, the
first function disregards the interference caused to a first cell
by a second cell when the first cell and the second cell have
different PCI mod 3 values according to the current combination. In
other words, the first function takes into account the interference
caused to the first cell by the second cell only when the first
cell and the second cell have the same PCI mod 3 value according to
the current combination.
[0036] Step 208 then comprises determining which combination
provides the output fulfilling a predefined criterion. In an
embodiment, the predefined criterion comprises minimizing or
maximizing the output of the first function. Thus, it may be
detected which combination of PCI-mod 3 values minimizes the first
function, for example. The minimization/maximization of the
function (e.g. a cell adjacency metric) may be performed by using
an arbitrary global optimization search scheme.
[0037] In step 210, those PCI mod 3 values, which correspond to the
output fulfilling the predefined criterion, are selected and
allocated to the plurality of cells of the network 100. In this
manner, optimized PCI mod 3 values (i.e. the N.sub.ID2 values) are
established and allocated to the cells. The optimality of the PCI
mod 3 values is due to the fact that the predetermined function may
be seen as a cell adjacency metric taking into account the radio
frequency signal levels with respect to plurality of cells at
several locations in the network 100. E.g. by selecting such PCI
mod 3 values which provide the smallest possible cumulated
interference value in the network, the total amount of collisions
may be reduced and the performance of the network 100 and the key
performance indicators may be improved. It may also be noted that
the PCI mod 3 of the cell affects the PSS of the cell. By
allocating the PCI mod 3 values optimally, the collision of the
PSSs may be reduced and the reference signal detection performance
from the serving cells may be improved.
[0038] Let us now take a closer look at the possible options for
the first function to be applied in the PCI mod 3 allocation
procedure. For all the samples where cell i is the serving cell, at
each sample k, the power level (e.g. the RSRP) from the serving
cell is S.sub.i.sup.(k), and the power level of the interfering
cell j is I.sub.i,j.sup.(k). The noise level is
.sigma..sub.n.sup.2. In general, the PCI mod 3 values to be
allocated are optimized by minimizing the following metric shown in
Equation (1). That is, the first function may be expressed
generally as follows:
minimize c p PSS F ( S 1 ( 1 ) , , S 1 ( N loc , 1 ) , , S N cell (
1 ) , , S N cell ( N loc , N cell ) , g 1 , 2 I 1 , 2 ( 1 ) , , g 1
, 2 I 1 , 2 ( N loc , 1 ) , , g N cell , N cell - 1 I N cell N cell
- 1 ( 1 ) , , g N cell , N cell - 1 I N cell N cell - 1 ( N loc , N
cell ) ) such that g i , j = { 1 , c p , i PSS = c p , j PSS 0 ,
otherwise c p , i PSS = { 0 , 1 , 2 } ; c p , j PSS = { 0 , 1 , 2 }
( 1 ) ##EQU00001##
where N.sub.loc,i is the number of samples where cell i is the
serving cell, c.sub.p.sup.PSS is the p.sup.th candidate solution
which contains the candidate PCI mod 3 values for each of the
plurality of cells. E.g. if there are nine cells, as shown in FIG.
1, then c.sub.p.sup.PSS holds nine PCI mod 3 values.
c.sub.opt.sup.PSS is the optimized solution for the PCI mod 3
allocation. In the former example, c.sub.opt.sup.PSS comprises also
nine values, one for each cell.
[0039] The general form of the first function/equation may be offer
several options for the to-be-applied first function. In an
embodiment, the output of the first function represents a
cumulative interference detection rate or value among the plurality
of cells, wherein the first function takes into account the power
levels of interference determined for each of the several locations
N.sub.loc on the basis of the radio map 300. In other words, it may
be said that in this case the first function depicts the cumulative
inter-cell interference value or detection rate. An example option
for the first equation which aims in minimizing the rate of
inter-cell interference detection may be given as shown in Equation
(2):
minimize g i , j .mu. i = 1 N cell j = 1 , j .noteq. i N cell k = 1
N loc , i g i , j .delta. i , j ( k ) such that .delta. i , j ( k )
= { 1 , I i , j ( k ) > 0 0 , otherwise ( 2 ) ##EQU00002##
where .mu. is a normalization constant so that the corresponding
equation/function has a physical meaning. The normalization factor
.mu. may be any value to aid the analysis. For example, for this
Equation (2), when .mu. is 1, then the function (2) gives the
average number of same PCI mod 3 interfering cells per location k.
According to this Equation, at each location k, it is determined
whether there is interference detected from another cell. The
parameter g takes care that only cells having the same PCI mod 3
candidate are taken into account. That is interference from a cell
with different PCI mod 3 is disregarded. This is because cells
which are allocated another PCI mod 3 do not interfere each other's
PSS transmissions. For example, looking at FIG. 3, assuming that
the cells 102 and 106 have different PCI mod 3 value candidates and
the cells 104 and 106 have the same PCI mod 3 value candidate
according to the current tested combination, then the Equation (2)
does not take the interference level 312 from the cell 102 into
account, but only the interference level 314 coming from the cell
104.
[0040] It should be noted that instead of minimizing the rate of
detection of the inter-cell interference, the object could be to
minimize the amount of inter-cell interference detected. In such
case, the actual power levels of inter-cell interference (as
indicated with reference numeral 312 and 314 in FIG. 3) from those
cells which have the same PCI mod 3 candidate number as the serving
cell in the current combination may be accumulated together, for
example. Then, it may be detected which combination provides the
minimum value.
[0041] In another embodiment, the output of the first function
represents a cumulative value related to a signal-to-interference
(SIR) ratio or to a signal-to-interference-plus-noise (SINR) ratio,
wherein the first function takes into account the corresponding
ratios determined for each of the several locations N.sub.loc on
the basis of the radio map 300. In these cases the corresponding
first predetermined function may be given as shown with Equation
(3) aiming at minimizing the average (reference signal) 1/SIR:
minimize g i , j .mu. i = 1 N cell j = 1 , j .noteq. i N cell k = 1
N loc , i g i , j I i , k ( k ) / S i ( k ) ( 3 ) ##EQU00003##
[0042] and with Equation (4) aiming at maximizing the average
(reference signal) SINR:
maximize g i , j .mu. i = 1 N cell k = 1 N loc , i s i ( k ) j = 1
, j .noteq. i N cell g i , j I i , j ( k ) + .sigma. n 2 ( 4 )
##EQU00004##
[0043] As shown, the SIR or SINR values may be obtained from the
radio map 300 indicating the power levels of the desired signal,
the power levels of interfering signals and the noise levels at
each of the several locations N.sub.loc with respect to each cell.
The applied RF signal levels of the radio map 300 may be based on
the reference signals (RS/CRS).
[0044] In yet another embodiment, the output of the first function
represents a cumulative throughput in the network 100, wherein the
first function takes into account the throughputs determined for
each of the several locationsN.sub.loc on the basis of the radio
map 300. In this embodiment, the first function/equation may be
given as:
maximize g i , j .mu. i = 1 N cell k = 1 N loc , i .beta. ( s i ( k
) j = 1 , j .noteq. i N cell g i , j I i , j ( k ) + .sigma. n 2 )
( 5 ) ##EQU00005##
where .beta.(SINR) is the throughput of the UE as a function of the
SINR.
[0045] It should be noted that other selections for the first
function are possible as well, including maximizing the cell-edge
throughput, minimizing detected amount of interference within a SIR
threshold, minimizing the rate of detection of interference within
the SIR threshold, etc. The threshold may be empirically derived or
base on simulations. For example, in Equation (2), a threshold
different than zero (0) could be used, in which case the
interference is counted as detected only if the detected inter-cell
interference from a certain cell exceeds a given non-zero
threshold. The required parameters may be based on reference signal
(RS) measurements or predictions, such as on RSRPs at several
locations N.sub.loc in the network 100.
[0046] The interference levels, the SIR ratios, the SINR ratios,
and/or the throughputs may be determined for each of the plurality
cells in the network 100 at several locations of the network 100 on
the basis of the radio map 300. It may be that the UE 308 has
itself transmitted information indicating the needed
parameters/parameter values (such as the detected interference for
each cell) to the network element responsible of the PCI allocation
so that the network element may build the map 300. Alternatively,
the network element may have used simulation/prediction tools known
to skilled person in order to acquire the radio map 300 comprising
the needed parameters. Then, depending on the candidate
c.sub.p.sup.PSS the outcome of the selected first function may vary
because the effect of inter-cell interference in the network is
based on the allocation of the PCI mod 3 values. Finally, those PCI
mod 3 values, which correspond to the output fulfilling the
predefined criterion (i.e. minimize or maximize the first
function), are selected and allocated to the plurality of cells of
the network 100. Accordingly, the proposal may allow planning the
PCIs to minimize CRC/PSS collisions.
[0047] Now that the PCI mod 3 has been allocated optimally to the
cells of the network 100, the PCI modulo 30 values may then be
allocated, at least when the PUCCH DMRS collisions are to be
avoided. For each PCI mod 3 grouping (group of cells with the same
PCI mod 3 value), the PCI mod 30 values are allocated in a similar
fashion as the PCI mod 3 values were allocated. E.g. by minimizing
the average 1/(SIR), maximizing the average SINR, maximizing the
average throughput or cell-edge throughput. This is shown in FIG.
5. After having allocated the PCI modulo 3 values for the plurality
of cells in step 210, the network element responsible of PCI
allocation may perform the steps 500 to 510.
[0048] In step 500 it is determined which of the plurality of cells
have the same PCI modulo 3 value. If there are only three cells in
the network, then each of them may have a different PCI mod 3
value. However, when there is more cells, then some of the cells
are bound to have the same PCI mod 3 value. It may be important to
be able to allocate PCI mod 30 values to those cells optimally,
e.g. to allocate a different PCI mod 30 value to each of those
cells having the same PCI mod 3 value. The available numbers for
the PCI mod 30 range from 0 to 29. It should be noted that by
allocating different PCI mod 3 values to some cells, then the PCI
mod 30 is automatically different for those cell. Consequently,
those cells need not be considered in the procedure of FIG. 5.
However, it may be that the PCI mod 3 is the same for some cells.
As the search space may be the same for many cells, then it may be
important to optimally select which cells are allocated with which
PCI mod 30 values. For example, neighboring cells may
advantageously be assigned different PCI mod 30 values.
[0049] In step 502, the network element may select a second
function to be applied, wherein the second function is at least
partly based on the radio map 300 and comprises PCI mod 30 values
for the cells having the same PCI mod 3 value as input variables.
Thus, the second function may be similar as the first function. In
an embodiment, the applied second function is the same as the
applied first function.
[0050] The to-be-applied second function may be selected from the
same group as the first function was selected. That is, it may
represent the cumulative interference, the cumulative SIR or SINR,
the cumulative throughput, the cumulative cell-edge throughput, the
cumulative interference within a SIR threshold, the cumulative rate
of detection of interference, etc. in the network 100 among the
cells having the same PCI mod 3 values. In general, the second
function may be given as:
minimize c p SSSGroup F ( S 1 ( 1 ) , , S 1 ( N loc , 1 ) , , S N
cell ( 1 ) , , S N cell ( N loc , N cell ) , g 1 , 2 I 1 , 2 ( 1 )
, , g 1 , 2 I 1 , 2 ( N loc , 1 ) , , g N cell , N cell - 1 I N
cell N cell - 1 ( 1 ) , , g N cell , N cell - 1 I N cell N cell - 1
( N loc , N cell ) ) such that g i , j = { 1 , c p , i SSSGroup = c
p , j SSSGroup 0 , otherwise c p , i SSSGroup = { 0 , 1 , , 29 } ,
c p , i SSSGroup mod 3 = c opt , i PSS c p , j SSSGroup = { 0 , 1 ,
, 29 } , c p , j SSSGroup mod 3 = c opt , j PSS ( 6 )
##EQU00006##
where C.sub.p.sup.SSSGroup is the p.sup.th candidate solution which
contains the candidate PCI mod 30 values for all the cells having
the same PCI mod 3 value. A parameter c.sub.opt.sup.SSSGroup is the
optimized solution for PCI mod 30 allocation for these cells. In
Equation (6), the cells are assumed to run from 1 to N.sub.cell
even though some cells may be bypassed depending on what the
earlier allocated PCI mod 3 of the cell is. For example, when
performing the PCI mod 30 allocation for the cells having PCI mod
3=0, then all the cells which have been allocated with PCI mod 3=1
or with PCI mod 3=2 may be bypassed and/or disregarded.
[0051] In step 504, the network element may apply different
combinations of the PCI mod 30 values in/to the second function,
wherein each candidate PCI mod 30 value is selected from a group of
thirty available options, such as from {0, 1, 2, . . . , 29}.
However, in an embodiment this group may be narrowed down from
thirty by requiring that each candidate PCI modulo 30 value for a
certain cell i fulfills a following condition: a modulo 3
arithmetic performed for the candidate PCI modulo 30 value is the
same as previously (in step 210) allocated PCI modulo 3 value for
the same certain cell i. That is, by forcing the candidate values
to fulfill the criterion according to which c.sub.p,i.sup.SSSGroup
mod 3=c.sub.opt,i.sup.PSS. This is because if the PCI mod 3 for the
cell i is determined to be 1, then a PCI mod 30 value of 6, for
example, cannot be allocated to the cell i as such allocation would
not fulfill the PCI mod 3=1 allocation.
[0052] For example, let us assume that for cells i and j the PCI
mod 3 is 1 (i.e. c.sub.opt,i.sup.PSS=c.sub.opt,j.sup.PSS=1). In
such case, the possible PCI values fulfilling the PCI mod 3
criterion are {1, 4, 7, . . . , 31, 34, . . . , 163, 166, . . . ,
499, 502}. Remember that possible PCI values may range in the LTE
from 0 to 503, as explained above. Now instead of pursuing the
whole range {0, 1, . . . , 29}, this range may be narrowed down.
When modulo 30 arithmetic is applied to these possible PCI values,
the following numbers are obtained: {1, 4, 7, 10, 13, 16, 19, 22,
25, 28}. In other words, if the PCI mod 3 already dictates that the
PCI may not be, for example, 2 or 3, then such PCI mod 30 values
need not be considered. Thus, the values {1, 4, 7, 10, 13, 16, 19,
22, 25, 28} may be the search space for the PCI mod 30 values (i.e.
the available candidate PCI mod 30 values) for the cells i and
j.
[0053] In step 506, the output of the second function with respect
to each combination may be determined. As was the case for the
first function, in an embodiment, the second function may disregard
the inter-cell interference caused to a first cell by a second cell
when the first cell and the second cell have different candidate
PCI mod 30 values according to the current combination. This may be
because when the cells have different PCI mod 30 values, they also
have different PUCCH DMRS sequences. Having different PCI mod 30
may advantageously lead to the use of different DMRSs and decrease
of DMRS collisions. Accordingly, the embodiment may allow planning
the PCIs to minimize PUCCH DMRS collisions.
[0054] In step 508 it may be determined which combination provides
the output fulfilling a second predefined criterion. The second
predefined criterion may in an embodiment comprise minimizing or
maximizing the output of second function. Finally, in step 510, the
network element may allocate those PCI mod 30 values, which
correspond to the output fulfilling the second predefined
criterion, to the cells having the same PCI mod 3 value. This may
be done to reduce the interference between the PUCCH DMRSs of the
cells. The determined optimized PCI mod 30 value for a cell j may
indicate a group of allowable PCI values for the cell j. For
example, if the selected PCI mod 30 for cell j is determined to be
10 (i.e. c.sub.opt,j.sup.SSSGroup=10), then the PCI to be allocated
to the cell j needs to be selected from a group of {10, 40, 70,
100, . . . , 470, 500}. These values also imply that the allocated
PCI mod 3 value for the cell j is 1, (i.e.
c.sub.opt,i.sup.PSS=1).
[0055] Now that the PCI mod 3 values (i.e. the N.sub.ID2) and the
PCI mod 30 values have been allocated to each cell in an optimal
manner, the network element may in step 600 determine the PCI for
each of the plurality of cells on the basis of the allocated PCI
modulo 3 values/numbers and the allocated PCI modulo 30
values/numbers, and finally, in step 602, allocate the determined
PCIs for each of the plurality of cells of the network 100.
[0056] Accordingly, the PCIs from a group {0, 1, 2, . . . , 502}
may be arbitrarily selected as long as the allocation fulfils the
following criteria: [0057] Modulo 30 arithmetic of the assigned PCI
for cell i must be the same as the previously (in step 510)
allocated PCI mod 30 value, i.e. PCI.sub.i mod
30=c.sub.opt,i.sup.PSSGroup. This is reasonable so that the
allocations performed in steps 210 and 510 of FIGS. 2 and 5 are
used as a basis for the final PCI allocation and are not overruled.
It should be noted that this requirement/condition/constraint holds
when the PCI mod 30 values are allocated according to FIG. 5 to the
cells of the network 100. [0058] Neighbour cells and
neighbour-of-neighbour cells must not have the same PCI in order to
avoid confusion during handovers. Thus, these neighbour and
neighbour-of-neighbor cells are advantageously allocated different
PCIs. In an embodiment, a neighbour cell is a cell that is
registered in an eNB, which may be the source or target of a
handover. This may be put in an Equation as
[0058] v i , j = { 1 , site i and j are neighbors 0 , otherwise ( 7
) w i , j = { 1 , site i and j are neighbor - of - neighbors 0 ,
otherwise ( 8 ) ##EQU00007##
[0059] Further, as optional requirement, there may be defined some
blacklisted PCI which are not used for selection. These blacklisted
PCIs may be PCIs that are known to result in inefficient throughput
or increase of interference, for example.
[0060] As another optional constraint, there may be requirement
that minimum site-to-site distance thresholds are followed. Such
site-to-site distance may imply the physical distance between the
transmission points, regardless of whether or not their coverage
areas overlap. This means that if the distance between cells i and
j is large enough (threshold may be based on empirical derivation
or simulations, for example), the cells i and j may be allocated
the same PCI. If the distance is less than the threshold, the cells
i and j should be allocated with different PCIs. In the form of
Equation this may be given as:
d i , j = { 1 , dist i , j site - to - site .ltoreq. d threshold
site - to - site 0 , otherwise ( 9 ) ##EQU00008##
[0061] As a further optional requirement, cells of the same site m
(such as of the same eNB) must have the same value of PCI.sub.m/3.
This may be especially useful for sites with three sectors/cells.
In other words, these cells are forced to have the same SSS
sequence, i.e. the same N.sub.ID1. Then, the three cells of the
same site 102 may each have different PSS (i.e. the N.sub.ID2 of
each of the three sectors is different).
[0062] The allocation of the final physical layer cell identities
(PCIs) to the cell may, based on the above, be given as a
minimization problem according to the Equation (10) below:
minimize PCI i .mu. i = 1 N cell j = 1 , j .noteq. i N cell q i F (
S i , I i , j , d i , j v i , j , w i , j ) such that q i = { 1 ,
PCI j = PCI j 0 , otherwise ( 10 ) ##EQU00009##
[0063] By solving this minimization problem, the PCIs for the cells
of the network 100 may be obtained. Consequently, the proposal may
allow optimizing the PCIs to minimize CRC/PSS/PUCCH DMRS
collisions. For example, as shown in FIG. 7, at least three cells
from different eNBs 102, 104, 106 may overlap in the area 110.
According to the optimized PCI planning, the overlapping cells may
be allocated with different PCI mod 3 values and different PCI mod
30 values, as shown. Note that the given example values are simply
for illustrative purposes.
[0064] The given minimization/maximization problems of some of the
embodiments may be non-deterministic polynomial-time (NP)--hard.
Therefore, the method of global search for the solution may be
selected from the available options known to a skilled person. Some
examples of such available options comprise simulated annealing,
tabu-search, genetic and evolutionary algorithms, for example.
[0065] As explained above, the proposal may result in the
allocation of the PCIs to the cells. This may be performed in a
three-step procedure. In the step 1, the allocation of the PCI mod
3 may be made for example according to FIG. 2 in order to minimize
CRS and PSS interferences. In step 2, the allocation of the PCI mod
30 based on PCI mod 3 grouping is made for example according to
FIG. 5 in order to minimize DMRS interferences. Finally, in step 3
the PCIs are allocated based on the PCI mod 30 and/or PCI mod 3
allocations for example in order to avoid the neighbors and
neighbors-of-neighbors to have the same PCIs. This may enable a
provider of a network, such as an operator, to provide an efficient
and a customer-friendly communication network to the end-users.
[0066] An embodiment, as shown in FIG. 8, provides an apparatus 800
comprising a control circuitry (CTRL) 802, such as at least one
processor, and at least one memory 804 including a computer program
code (PROG), wherein the at least one memory 804 and the computer
program code (PROG), are configured, with the at least one
processor 802 to cause the apparatus 800 to carry out any one of
the embodiments. The memory 804 may be implemented using any
suitable data storage technology, such as semiconductor based
memory devices, flash memory, magnetic memory devices and systems,
optical memory devices and systems, fixed memory and removable
memory.
[0067] The apparatus 800 may be any entity or logical element in
the network 100 responsible of performing the PCI planning and
allocations to the network 100. For example, the apparatus 800 may
be a part of the EPC of the LTE or the LTE-A.
[0068] The control circuitry 802 may comprise a radio map
generation circuitry 810 for generating the radio map 300,
according to any of the embodiments. The apparatus 800 may store
the map in the memory 804, for example.
[0069] The control circuitry 802 may further comprise a PCI mod 3
and a PCI mod 30 allocation circuitry or module 812 for the
allocation of the PCI mod 3 values and the PCI mod 30 values,
according to any of the embodiments. The circuitry 812 may
communicate with an equation selection circuitry 814 for selecting
the first and the second functions to be applied in the allocation
processes according to FIGS. 2 and 5, for example. The control
circuitry 802 may thus comprise information of the
equations/functions 816. The apparatus 800 may, for example, store
the equations/functions in the memory 804.
[0070] The control circuitry 802 may further comprise PCI
allocation circuitry 818 for allocating the PCI, according to any
of the embodiments. The circuitry 818 may communicate with a
constraints/condition selection circuitry 820 which may be
responsible of selecting constraints/conditions 822 applied in the
PCI allocation. The constraints 822 may be stored in the memory
804, for example. Possible constraint may include the distance
thresholds, blacklisted PCIs, same SSS requirement for three-sector
sited, etc.
[0071] The apparatus 800 may further comprise a communication
interface (TRX) 806 comprising hardware and/or software for
realizing communication connectivity according to one or more
communication protocols. The TRX 806 may provide the apparatus with
communication capabilities to access the radio access network, for
example.
[0072] The apparatus 800 may also comprise a user interface 808
comprising, for example, at least one keypad, a microphone, a touch
display, a display, a speaker, etc. The user interface 808 may be
used to control the apparatus 800 by the user.
[0073] As used in this application, the term `circuitry` refers to
all of the following: (a) hardware-only circuit implementations,
such as implementations in only analog and/or digital circuitry,
and (b) combinations of circuits and software (and/or firmware),
such as (as applicable): (i) a combination of processor(s) or (ii)
portions of processor(s)/software including digital signal
processor(s), software, and memory(ies) that work together to cause
an apparatus to perform various functions, and (c) circuits, such
as a microprocessor(s) or a portion of a microprocessor(s), that
require software or firmware for operation, even if the software or
firmware is not physically present. This definition of `circuitry`
applies to all uses of this term in this application. As a further
example, as used in this application, the term `circuitry` would
also cover an implementation of merely a processor (or multiple
processors) or a portion of a processor and its (or their)
accompanying software and/or firmware. The term `circuitry` would
also cover, for example and if applicable to the particular
element, a baseband integrated circuit or applications processor
integrated circuit for a mobile phone or a similar integrated
circuit in a server, a cellular network device, or another network
device.
[0074] The techniques and methods described herein may be
implemented by various means. For example, these techniques may be
implemented in hardware (one or more devices), firmware (one or
more devices), software (one or more modules), or combinations
thereof. For a hardware implementation, the apparatus(es) of
embodiments may be implemented within one or more
application-specific integrated circuits (ASICs), digital signal
processors (DSPs), digital signal processing devices (DSPDs),
programmable logic devices (PLDs), field programmable gate arrays
(FPGAs), processors, controllers, micro-controllers,
microprocessors, other electronic units designed to perform the
functions described herein, or a combination thereof. For firmware
or software, the implementation can be carried out through modules
of at least one chip set (e.g. procedures, functions, and so on)
that perform the functions described herein. The software codes may
be stored in a memory unit and executed by processors. The memory
unit may be implemented within the processor or externally to the
processor. In the latter case, it can be communicatively coupled to
the processor via various means, as is known in the art.
Additionally, the components of the systems described herein may be
rearranged and/or complemented by additional components in order to
facilitate the achievements of the various aspects, etc., described
with regard thereto, and they are not limited to the precise
configurations set forth in the given figures, as will be
appreciated by one skilled in the art.
[0075] Embodiments as described may also be carried out in the form
of a computer process defined by a computer program. The computer
program may be in source code form, object code form, or in some
intermediate form, and it may be stored in some sort of carrier,
which may be any entity or device capable of carrying the program.
For example, the computer program may be stored on a computer
program distribution medium readable by a computer or a processor.
The computer program medium may be, for example but not limited to,
a record medium, computer memory, read-only memory, electrical
carrier signal, telecommunications signal, and software
distribution package, for example. Coding of software for carrying
out the embodiments as shown and described is well within the scope
of a person of ordinary skill in the art.
[0076] Even though the invention has been described above with
reference to an example according to the accompanying drawings, it
is clear that the invention is not restricted thereto but can be
modified in several ways within the scope of the appended claims.
Therefore, all words and expressions should be interpreted broadly
and they are intended to illustrate, not to restrict, the
embodiment. It will be obvious to a person skilled in the art that,
as technology advances, the inventive concept can be implemented in
various ways. Further, it is clear to a person skilled in the art
that the described embodiments may, but are not required to, be
combined with other embodiments in various ways.
* * * * *